NIOSH Information Circular - 9496

Page 48: RFID tags are now typically 96 bits.

Pages 48 reads:

Radio frequency identification (RFID) is an emerging subset of wireless technology.
RFID devices are known as tags, as they "tag" an object or person with a small device containing
a large binary number, typically 48 bits or 2.8 × 1014 different numbers.

The "48 bits" was correct when the initial RFID section was
written. Today EPCGlobal has set the
standard to be 96 bits or 7.9 x 1028 for the simple
tags. More complex tags, especially "Active Tags" can store
several thousand kilobytes of data.